In practice, such contours, points or works are prepared on the basis of various working drawings and construction drawings. Based on these drawings, the contours, points and/or works in question are subsequently set out or marked out on an object or in a three-dimensional space for realising the same.
Optical or laser-controlled levelling instruments and the like are traditionally used for relatively large-sized projects, such as bridges, flyovers, parks or large buildings, wherein the contour, point or work to be realised is marked out in the space on the basis of one or more reference points in the space, for example pegs set out by a land surveying organisation.
The traditional way of setting out contours, points or works, using an optical levelling instrument, staffs and measuring tape is time-consuming in practice, especially when setting out complex, non-straight contours in a vertical, inclined or curved plane and in the case of works with a relatively great variation in height. Because at least two persons having specialist knowledge are needed, this is a rather costly method of working.
In practice, the accuracy of projects carried out by means of optical or laser-controlled equipment is to a high degree influenced by ambient conditions, such as the incidence of light, shadow effects, temperature, etc. In order to obtain a sufficiently accurate result, a number of measurements are carried out for every point, which is not conducive to realising a high working speed when using such equipment.
For relatively small projects, for example in the order of up to a few metres, such as the setting out in a space or on objects of contours or points of windows, doors, shafts, ducts, the course of water conduits and/or electrical conduits or of a sewer system or a drainage system in a building, of works such as production moulds in a factory and machining positions, such as holes to be drilled or grooves to be milled, on products or objects and the like, it is generally not possible to use laser-controlled levelling instruments, because of the relatively large dimensions of such instruments, which necessitate frequent repositioning and recalibration of the instruments, for example when setting out contours or points in a relatively small space, but also because of their limited precision and the aforesaid effect of ambient conditions on the measurement.
From European patent No. 1 226 401 and the subsequent U.S. Pat. No. 7,395,609 B2 measuring devices for measuring the position of a movable measuring probe in two or three independent coordinates are known. These known measuring devices are based on the same measuring principle and comprise a base unit in which the movable measuring probe is connected to a measuring device incorporated in the base unit via a cord or a wire and a rotatably supported elongate arm. The measuring device is provided with sensors for measuring a length or a change in the length of the cord or the wire and rotation of the arm in at least one degree of freedom while the measuring probe is being moved. A computer-controlled processing device connected to the sensors processes the measuring signals delivered by the sensors into position data of the measuring probe and makes these data available on a communication interface.
The measuring apparatuses known from European patent No. 1 226 401 are marketed in a two-dimensional measuring version or in a three-dimensional measuring version under the trade name Proliner® by the Assignee of the present patent application. The Proliner® is capable of measuring the (spatial) position of individual points at a high speed and with a high degree of precision. The measuring apparatuses have a handy size, they can be installed in a very short time and they are very user-friendly. Using the Proliner®, also non-expert users are able to measure complex contours and works in the order of a few metres in a quick and accurate manner.